#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCRN_WIDTH 128
#define SCRN_HEIGHT 64
#define OLED_RESET -1
uint32_t I2C_clock = 1000000;

Adafruit_SSD1306 display(SCRN_WIDTH, SCRN_HEIGHT, &Wire, OLED_RESET, I2C_clock, I2C_clock);

uint32_t thisMicros = 0;
uint32_t lastMicros = 0;

void setup()   {
    Wire.begin();
    Wire.setClock(I2C_clock);
    display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
    display.display();
    display.clearDisplay();
    display.setTextSize(1);
    display.setTextColor(WHITE);
}

void loop()
{
    thisMicros = micros();
    display.clearDisplay();
    display.setCursor(0,0);
    display.print(thisMicros - lastMicros);
    display.display();
    lastMicros = thisMicros;
}